CA1048351A - Magnetic films of transition metal-rare earth alloys - Google Patents

Abstract

MAGNETIC FILMS OF TRANSITION METAL-RARE EARTH ALLOYS
Abstract of the Disclosure A method of preparing a magnetic member composed of a non-magnetic substrate carrying a magnetic film of a transition metal-rare earth alloy comprising decomposing a rare earth metal compound below 1000°C to form a layer of rare earth metal on a substrate, decomposing a transition metal compound below 1000°C to form a layer of transition metal on the deposited rare earth metal, heating the metals to form an alloy thereof which has its preferred axis of magnetization substantially aligned and in a direction perpendicular to the plane of the substrate and magnetizing the film.

Description

~83Sl RD-5772 ~ ~ .
The present inv~ntion relates to the fo ~ tisn o~
magnetic ~ilms of tr~n~ition matal-r~re earth alloy~, In pQrtieular, it relates to th~ formstion o a magnetic me~ber compo~ed of a non-magnetic sub~trate carrying Q
oagn~tic film of a tran~ition me~ rare ear~h ~lloy, particularly a cobalt-r~re earth alloy, There are a numbQr of probl~ms lnherent in the ~ormation of magnetic films of transi~ion met~l-rare e~rth alloys, A~ a prac~lcal matter, ~puttering and other typ~a ~ ~
o~ electron beam evaporation c~nno~ he used becaus~ t~e ~ .
rare ear~h metal i8 very reac~ive in the sputterlng and/or . .
electron beam evaporation atm~sphqre, and accordingly, ge~ters a very substantial amou~t o~ r~3idua1 oxygen unle~s elaborate precautlon~ ag~inst this hsppening are taken~
Alsos the u~e oP either of these tech~iquefi does not give uniform, pore-free coherent coatings, part~c~larly when complex g~mQtrl2s ~re involved.
Coaventional avapora~ion technique~ al~o ha~e a num~er of drawback~. One draw~ck i8 t~at the tr~n31tivn 20 metal~ u~eful h~r~ln h~e ~ry high m~l~ing po~nts.
Speci~ically, cobalt m~lts at 1480C., l~on at 1530C., manganesa at 1260C.and nickel ac 1452C~ Such h~gh :~
-Dlelting polnts require ttat ~ substrate have an even higher ~elting point ~chereby limlt~g it to a very ew expensive . , '' .

, . . . . .

mQterial~ w~ich are 3ufficiently iner~ for condltions oiE
depo~ition, Al~o, except for ~amarium, ~e r~r~ earth slement3 have extremely l~w vapor pre~ure3 regardle~ o~
the temperatur~s used making v~por d~po~iltlon o~ these 5 el~en~s lmpr~ctical.
Th2 pre~n~ inventlon allo~s ~he ~ffect~e depo~ lon of ~ubsl:an~all~ uniform layer~ of transition metal and rar~ earth ~n~tal ~t temperatures bel~w lOOO~C.
in the desired thlcknes e80 Such low depos~cion temperatures 10 allow th~ use of ~ multitude of ~ub~tr~ce ~Daterials, The~e deposited layer~ are hea~ce;d and alloyed to form a contlnuou~ cohererlt ~llbstan~i~lly uniform iE~l~ of the -,~ ., desired alloy arld ~uch alloy film, when magnotized, tl~l8 propertie~ satis~ac~cory for a ~id~ range o~ mngnetic 15 ~pplication~ ~o ~er vapor or oxygen ga~ i8 present to degrade ~he ~gn0tic prop~rties of ~he alloy Briefly ~tated, the process of thz presen~
lnvention compri#es providing a ns~-magnetic 3ub~trate~
provlding a rar~ ~ar~h metal compound whlch is decompo~lble 20 at a temper~ur~ belaw 1000C. at atmo~pher~c pres~ur~
to yield the rare ~arth me~l vapor, contactlng the ~-resulting rare earth met~l v~por wlth said non-nmagnetic substra~e ~o depos~t a layer of t~e rare earth metal ~hereonJ pr~vlding a tran~ition metal compound whlch i~
25 decomposlble below lOOO~.at a~mo~p~eric pre~sure to yi~ld ~2-' , .' ' ' ~ ~ ,"

RD~5772 th~ tran~ition metal vapor, heatln~ said transition ~etQl c~mpound to dec~mpos~ i~ and yi21d the transltion me~al vapor, contacting the re~ulting transition metal vapor with said depo$ited l~y~r of rare earth metal to depo~it substantially coextensively ~her~on a layer of the transition ~et~l, hQating the deposited layers ~o produc~
an allo~ t~ereo in the fonm of a continuous filmg s~d alloy h2vlng a substantial amo~nt of it~ easy axiB of :
magne~iza~ion p2rpendlcuL~r ~o the plane o~ the substrate9 and ~pplying to sfiid alloy ilm belo~1 its Curie temperature a ma~netic field p~r~llel to it~ easy axi~ w~ich hs~ a . ~:
.-.
~agnitude that satura~e~ the film.
In the pre~ent proce~ a film of a magnetic ; transiti3n ~et~ are ~arth 8110y~ e,g~, TRE, w~ere T 1~ a translt~on met~l ~nd RE i~ a rar~ 2arth m~al, i~ for~ed, The transition m~t~l i8 selQcted frGm the group con~isting o cobaltg iron, nickel, mangane~e and 8110y8 thereo0 ; The r~r~ earth met~l i8 one o~ ~he 15 elements of the lanthanide seri~ h~vlng ~omic numbers 57 to 71 inclu~ive ~;
a~ well as ~h~ elem2nt y~trl~m (~tomic number 39) which i8 c~mmonly includQd in thl~ group of metal~ and which, ln ~ :
this speci~ication, i~ considered a rare earth metal~ The ~` pr~sent ~agnetic fi~m can be co~po~ed of a pl~ral`ity of m~tal~ depending upon the partlcul~r proper~i~e de~lred.

: 3 ., ~ ' ' ;

3~ 5772 Tran~ition me'cal-rare ear~h interme~allic alloys or compound~ exist ln ~ v~ri~ty of phase~ and each phase msy vary ln composition. A m~terial sub3tantia~1y compri3~d of the T5RE ~ingle pha~e i~ par~cicularly pr¢~erred 5 in tha present invention ~i~ce ~his p~ase ~ ~ho~m the mo~t de~ir~ble comb~natlon of ~agnatic propertie30 l?ilm~ o:E the cobalt-rare earth ~lloys, are paricttlarly pre~rred due to their desirable permanen~
~agne~ prvper~ies. Represe~ta~ive o~ the cobalt-rare e~rth lQ comp~und~ or al~oys u~e~l irl the pre~en~ in~ntion ara cobalt-cerium, cobal~pra~eodym~um" cobalt-neody~
c~bal~-peome~hiu~, cobalt~sa~riu~7 cobalt-europiu~
cob~lt-gadollnlum, co~alt-erb~u~9 cobalt-t~uliu~
cob~lt-yt~erb~m, cobalt-lu~ocium, cobalt~ytkr~
cobalt-lanth~num ~nd ~obalt~ ek~etal. Example~ of ~peciic t~rnary compound~ include cobalt-ce~ium-praseodymium, cobalt~yttrium-pras~odymium, a~d cobalt-pra~eodymlum-mischMetal, In carrying out the pre~en~ proces~, an organ~c :
or inorganic compound of a rare earth metal and a tran~ition ~t~l ~8 us~d sequen~i~lly whleh decompo~es a~ ~ tempera~ure bel~w 1000C, at ~tm~spher~c pr~sure ~o yield the ~e~pective metal in ~ap~r ~o~m~ Each me~al vapor i8 sequent~ally condensed on Ehe ~ubstra~ to fon~ a continuou~ s~b~t~n~ially unl~Dn~ coating or layer of m~

... .

' 1 ~ 4 8 ~ 5 ~ RD-5772 thereon. The 8peciflc thicknes~ of each deposlted ~ayer o metal depends on thè amount necessary for the ~ubscquent ~onmation of the desired alloy ilm, e~g, substantially all of each metal pre~ent i8 u8ed ln formin~ the alloy f~lm.
The deposited metals are then heated in n ~mosphers in which thQy are ~ub~an~ially inert to form the desired ~;
alloy film, A8 the ~lloy i8 formed, the easy or preferred ;~
axis o~ magnetlzation of t~e alloy film aligns to a igni~
ficant extent and in ~ direc~lon perpendicular to the pl~ne of t~e sub8trate, ~he pr~qent procass mu~ be carried out in an atmospher2 in which the reacta~t~ are inert. It can be : :
carried out in an atmosp~ere such a~ argon or in a vacuu~
or par~ial v~cuum or in many instance~ in hydrogen..
The non~m~tallic product5 of decompo8ition ar~ ;
gaseouB and remDvabl~ by a number of con~en~ion~l ~echniques such a8, ~or e~ample, by a flowin~ atmo~phere or a vacuum.
S~nce the non-metalLlc produet8 o~ d~compo5itlon are mucb le8~ dense and signi~lcantly more ea~ily v~porizable than the depo~ited metal, they do not ~nterere wi~h ~he ; conden8at~0n of the metal vapor i~ ~he formatlon of continuous metal coatings in t~e preeent invention. The rare earth metal compound or tr~D8i~ion metal compound used ln the present lnvention can be a solid, liquid or gas a~
room temperature, The amount of compound o~ tran81~ion mRtal or ~ar~ earth metal u~ed i8 detenminable empirlcally, : ~5_ :

4~ 5772 It should be used ln an amount which, on decomposition~ i~
~ufflcient to produce ~ significant partial pres~ura of metal vapor to effectively coa~c the expo~ed surface of the ~ub~trate to form a continuous coating or l~yer of m~t~l :
5 t~ereon in the de~lred thick~ess. Specl~ically, the p~rtlcular compound used should, when decomposQd, y~eld a - .:
partial preP~ure of ~tal vapor of at least about 10~7 8t~nosphere" sufficient tG effect~aly depo~it ~ layer of ~atal on the expo~ed ~urf~ce of the 3ubstrate. The ~: 10 cosn~osmd of ~cran31tion metal or r~re earth metal may decompose to yi~ld the respective ~etal vapor directly or :
it ~ay d~canpo~e to yleld a vapor ~hich i~ then decompo8ed to give ~he metai or m~tal v~por~ Representat~ve of th~
~are earth metal organic compolmds useful in the present inventlon are the rare earth hexafluoroacteylacetonates w~ich decompose at a ~emp~rat~re of about 275C. For .
~: ex~mple, neody~ium hexaf~uoroacetylacetonate decompo~es to yield neodymlum vapcr d~rectly. Al30 u~eful are the -tricyclopent~dienyl rare earth c~pounds o~ yttrium~

20 lanth~num, cerium, pra~eodymi~L~n, neodymium, ~amar~

~dolinium, dy~prosium" erbium ~nd ytterbium. Atdltional i useful examples are the dicyclopentsdienyl chlorides of ~:

; the r re earth me~als which ~re reduclble by hydrogen to ~ ~

~orm the hydrides w~lch decompo~e readily ~t temperatures :

below 1000C. to produc~ the rare earth metal. ~cept . : ;~

or samarlum, erbium and y~terblum, the rar~ earth chlorldes, ~ .
~6- :

. .

bromides and opdodes are redicible by hydrogen to yield the rare earth metal.
Representative of the transition metal organic compounds useful in the present invention are the acetyl-acetonates, the hexafluoroacetylacetonates and the dicyclopentadienyls of cobalt, iron, manganese and nickel.
Additional useful compounds are the carbonyls of cobalt, iron, manganese and nickel.
Representative of the inorganic transition metal compounds useful in the present invention are CoCl3, CoBr3, NiCl2, NiBr2, FeCl3, FeBr3, MnCl2 and MnBr2.
In the present invention, the alloy film can be composed of more than one transition metal or rare earth metal depending on the particular properties desired. A
plurality of metals, for example Co, Mn and Sm can be deposited sequentially in layers in the proportion desired in the alloy and the deposited metals than heated to form the desired alloy film.
In the present invention, the substrate is a solid and should be non-magnetic or so weakly magnetic as not to diminish the magnetic properties of the magnetic film of transition metal-rare earth metal alloy formed thereon.
The substrate must be substantially inert to the conditions of deposition. The size and shape of the substrate is not critical. It can be flexible or rigid depending on the 3~ ~ ~ ~
RD-5772 :~
particular desired appl i¢ation, For example, the substrate ~n bo in the form of a ~ape, foil, wire or plate, Typical 8ubstrate~ are glass, pla~ic and non-magnetic metals quch as a~uminum and copperO
~he thickness ~nd 8p~ci~ic compo~ition of the ;;
alloy film formed on ~che sub3trate depend on ~he particular propertias de~ired, 5pecifica~1y, the alloy film i~ formed . ~
from at lea3t a f~lm-forming thic~ess o~ each deposited `:
metal. Generally3 ~he alloy film ranges ~rom abou~c 100 10 Ang~troms 'co about 10~00 An~troms, and for mo~t -, applicatlons requiring magnetic thin film~, film~ ranging in ~hickrles~ from about 300 Ang~trom~ to 1000 Angstrom8 are :~
8atisfactory.
A magnetic field is applied, preferably at room 15 temperature, to tho alloy film to rnagnetl~e ~he film. . ~ :
The magnetic field i~ applied parallel to the ea8y or preferred axi~ of magnati~ation of the ilm which in the present inventlon i8 perpendicular to the pl~ne of the :
~ub~trate. The magnet~c ~ield ~hould b~ of a mag~itude .-20 which ~atura~e~ th~ ~ilm to magnetize lt ~miformly. In the pr~sent proee~, a nagne~cic field of about 5û kiloersteds to 100 kiloersteds i8 u~ually ~u~ficient, A stronger magnetic field ma~r be 1~sed, but ge~erally has little add~ tional effsct o8 ' ' ~

~ ' . , . ~ , ., , . - , ~ ., ' ~. ' ' - ' '~ ~

RD~5772 ;
In one emb~dimsn~ of the pre3ent invention, the y fllm is provlded wl~h a c08t~ng of ~n inert non-magnetlc ma~c~rial which preveTlts oxidation and deteriora~ion o~ the magnetic properties of the alloy film. Such 5 protective coa'cing on the ~lloy film i8 pre~rably provlded before the alloy fiL~ i3 magn~zed~ Typical example.~ of the protec~i:ve coating are shellac and a cer~mic ~uch a~ ~llicon ~ltr~de w~ich can be vapor condensed onto the ~lloy ilm by ~he re~ction of silicon lO tetrschlorlde ~nd a~nia.
~,.
A number of conven~ional techniques can be used to carry out the present proce~s but such techniques m~lst allo~ the ~equeElti~l ~rmation or depo~ition of r~re earth ~ :~
metal and of tran8it:Lon r~e~al on tbe ~ubstrate surface, 15 Simllltaneous formation or d~position o rare earth metal ~nd tran~i~ion ~etal doe not psoduce the present magnetic -:: alloy film. Sp~c~fic~lly, ~ tA~eous ~onnation or ~:
déposition o~ r~re earth metal and tran~ition met~l and 3ubs~qllant he~tlng o~ thes~ ~etal~ to producc an alloy 20 oause~ nucleation of a multi~c~de o a micrograins which grow in rand~m dlrect$on~ resulting in an i~otroplc or random orie~t~tion of the preferred axi~ which cannot be aligned to produce a magne~c~c~lly anf~otropic m~terial.

, Th2 sequence o~ depo~iting or ~orming the ~etals in the 25 present proce~s i8 not critical, but if the particular _g_ ': ~
.

335~ 5772 rare ear~ch m8t~ oxidize~ re~dlly, it i~ pre~rably deposited lnitially on t~e substrate since subsequent deposition of ~he tran~ition metal thereon will Inhibit oxid~tion, S In one ~achnique of c~rrying out the prasent proces~9 ~he r~re e~r~h compound in vapor form i8 pa8Bed at a ~gnlficantly h~gl~ vapor pre~sur~ u~lng an inert atmosphere such a~ argon 8 a ca~erler ga3 ovar a de3~red ~ubstr~t~ which ~L8 heated to at least t~ d~compo~ition temperature o ~e coalpound vaporO The compound vapor deco~poses on cont ct with the hot ~ubstr~tQ leav~g a uniform coæting oiE the rare e~rth metal on th~ subs~cr~te, The rar~ earth compound vapor 1~ p~as~ed over ~he heated substra~ until the de~ired a~aount of r~re ear~ met~l, e.g, ~ ~ -the desired thickne~s of the l~yær o metal, h~ deposited on the ~ubstrate, The de~irad ~ransition me~al c~pound :
in ~rapor form can 8~11~rly be p~s~ed over the ~ub~tr~t~ ~;
to deposit the ~cr~tlRition met~l on~o the depo~ited rAr¢
e~rth met~l" Th~ 'cot~l ~mount~ of rara e~rth metal and transition met~l coated onto ~che substrate will deter~ e ~ :
the thicknea~ of ~he tran~it~on m~tal~rare e~rth alloy fil~
The relat~re ~mounts of r~re ~r~h met~al and l:ran~itlon metal pre ent will deke~ine the partlcul~r ~toichiometry of the final tranBition metal~-r~re e~rth alloy. In ~he :
deposltlon o~ rar~ earth and tr~n~itlon metals, ~re than one rare ear~h metal can b~ depo~ ed ~i~lt~naously ~10- , 3~
~_5772 and more than one ~cran~ition metal can be d~posited ~imultaneously a~ long ~18 depositiotl of r~re e~rt~ mstaL~
and tr~nsition m~tal~ i8 carried out sequentially.
~he pre~ant tranRition metal-xare e~rth alloy films exhibit a whole range of U~IQ~. ~or example, a tape, e~gO~ made of copper, coated with ~ highly magnetic tran~iLtion me~al~rar~ earth alloy9 for exas~ple Co5Sm, i~
e~sily wrapped to fon~ ~e ~gn~tlc: field in ~ ~Qotor or ganerator ~ssetnbly. Another ex~nple i8 the use o the present film~ a3 the ~ource of a magnetic field in a clrcuit u~ng the magnetic field ~enerated by the film to ~aint~ln the ~t~ility of ~ mechanical sy~tem, ~1BO~
these film~ ars use~ul in m~gnet~c bubble memory de~Tlces ~ .
and deep d~odes.
All pQrts and perc~ntage~ used herein are by weight unless o'cherwlse not~d. ~ .
~e inventlo~a is f~rther illu~trated by the followlng exan~ple, ~XAMPLE
A non-magnetlc substr~te of copper in the form o~
flexible tape having a width o~ about one-half inch i~
used, The tape i~ pl~ced in ~ reaction zone having an iner~
flowing atmosp~ere of argon at a pre~sure of about 760mm.Hg. ~ :
The tape i3 heated and ~2intsined a~ a t~perature of ~bout ` 25 600C.
The hexa~luDroacetylacetonate compound of 8amaxi~m i~ used ~nd 1~ h~ted at atmo~pheric preRsure in an a~mos-phere in which it ls ~ubstantially inert such a~ argon or, if preferred9 an ~rgon ~tmo~phere cont~ining hydrogen ~o Iceep oxygen lev~ls low. The compound o s$mariwm i8 vaporized ~t a temper~ture of about 400Co to yi~ld a vapor which has a partial pre~ure o a~ leaR~ 10-7 a~mo~phere and which i8 carried by ~he flowing iner~ a~mDsphere of argon through the reaction ~on~ over the hot coppQr substrate, A~ thc vapor con~act~ ~he hot copper surface, 1~ decomposas leaving s~mRrium metal thereon~ The vapor i~ pa~ ed over the hot copper surface to depo~it a rontinuous film 3f samarium metal thereon and in ~n amount sufficient to ~ub~equently fonm the 5Sm p~aR~ compound~
. Cob~lt h~xaflu~roacetylacetonate i~ heated ~t a~ s-pheric pres~ure in an atmo3phQrQ in which it i8 substantially iner~, ~urh aR ~rgon, at ~ te~pera~ure of about 400C. The result~ng vapor ha~ a partial pre~ure of a~ least 10 7 :~:
. ~ ~
atmosphere and i~ carried by the flowing ioert atmosphere of argon through the reaction zone ovar the depo~ited ~a~ar$um 20 and on contact wlth the hot ~ of samarium metal decomposes :~
leaving cobal~ metal deposited th~reon. The vapor is pas~ed over the deposited saulariu~ to depo~i a continuou~ layer of cob~lt metal thereon and in an ~noullt 3ufficlent to - ~ub~equently form the Co5Sm pha~e eompound when alloyed 25 wlth the deposited s~marium me~al, The proper am~unts of ~Y2~
' .
.. , , . . ~ .... . . .

, . . , :

5 ~
RD~5772 3amarium metal and cobalt to be d~posited are determinable empirically.
The resulting deposited layers of m~tal are then heated at atmospherlc pre~sure to ~ ~emperaturQ of about 800C in ~n atmo~phere in which ~hey are inert, such a~
~rgon, to alloy them and oDm ths CoSSm phase, The re~ultlng alloy fi~m hae a thicknesa o~ ~bout 300 An~strom~ and ha~ its easy ~i8 o m~gnet~z2tlon per~ :
pendicular to the plane of the subs~rate. A magnetl~ng ield of ~bou~ 50 kiloer3teds i~ applied at room temperature to the alloy ~ilm perpendicular to the plane of the~
substr~ and parallel to the ~a~y axi8 0~ magn~tization ~ ~
to magnetize ~he alloy fl~m and fonm a mag~etic ~ilm ~ .
sui~able ~or use in co~puters, ~ ~
: '~ `

- i ~13- :

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Claims (12)

The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:

1. A process of preparing a magnetic member consisting essentially of a non-magnetic solid substrate carrying a magnetically anisotropic film consisting of a transition metal-rare earth alloy which comprises providing a non-magnetic solid substrate, providing a rare earth metal compound wherein the rare earth metal component is selected from the group consisting of the 15 elements of the lanthanide series having atomic numbers 57 to 71 and the element yttrium and which is decomposible at a temperature below 1000°C at atmospheric pressure to yield the rare earth metal vapor, heating said rare earth metal compound to decompose it and yield the rare earth metal vapor, contacting the resulting rare earth metal vapor with said substrate to deposit a substantially uniform continuous layer of rare earth metal thereon, providing a transition metal compound wherein the transition metal component is selected from the group consisting of cobalt, iron, nickel, manganese and alloys thereof and which is decomposible at a temperature below 1000°C at atmospheric pressure to yield the transition metal vapor, heating said transition metal compound to decompose it and yield the transition metal vapor, contacting the resulting transition metal vapor with said deposited layer of rare earth metal to deposit substantially coextensively a substantially uniform continuous layer of the transition metal thereon, said substrate being substantially inert to the conditions of deposition, said process being carried out in an atmosphere in which metal compounds and said metals are inert, heating said layers forming a continuous coherent substantially uniform alloy film thereof, the thickness of said deposited layers of metal being dependent on the amount desired in said alloy film, said alloy film ranging in thickness from about 100 Angstroms to about 10,000 Angstroms, said alloy film having its easy axis of magnetization significantly aligned perpendicular to the plane of the substrate, and applying a magnetic field to said alloy film parallel to said easy axis which has a magnitude that saturates the film.

2. A process according to claim l wherein said nonmagnetic substrate is a flexible tape.

3. A process according to claim l wherein said alloy is an alloy of cobalt and samarium.

4. A process of preparing a magnetic member consisting essentially of a non-magnetic solid substrate carrying a magnetically anisotropic film consisting of a transition metal-rare earth alloy which comprises providing a non-magnetic substrate, providing a rare earth metal compound wherein the rare earth metal component is selected from the group consisting of the 15 elements of the lanthanide series having atomic numbers 57 to 71 and the element yttrium and which is decomposible at a temperature below 1000°C
pressure to yield the rare earth metal, heating said rare earth compound to vaporize it, contacting the resulting vapor of rare earth compound with said substrate to deposit a continuous layer of said rare earth compound thereon, heating said deposited compound in a reducing atmosphere to reduce the deposited compound and form a substantially uniform continuous layer of rare earth metal, providing a transition metal compound wherein the transition metal component is selected from the group consisting of cobalt, iron, nickel, manganese and alloys thereof and which is decomposible at a temperature below 1000°C at atmospheric pressure to yield the transition metal vapor, heating said transition metal compound to vaporize it, contacting the resulting vapor of transition metal compound with said deposited layer of rare earth metal to deposit substantially coextensively a continuous layer of said transition metal compound thereon, heating said deposited transition metal compound in a reducing atmosphere to reduce it and form a substantially uniform continuous layer of transition metal, heating said layers in an atmosphere in which they are substantially inert forming a continuous coherent substantially uniform alloy film thereof, the thickness of each thus-formed layer of metal being dependent on the amount desired in said alloy film, said alloy film having a thickness ranging from about 100 Angstroms to about 10,000 Angstroms, said alloy film having its easy axis of magnetization signifi-cantly aligned perpendicular to the plane of the substrate, and applying a magnetic field to said alloy film parallel to said easy axis which has a magnitude that saturates the film.

5. A process according to claim 4 wherein said non-magnetic substrate is a flexible tape.

6. A process according to claim 4 wherein said alloy is an alloy of cobalt and samarium.

7. A magnetic member consisting essentially of a non-magnetic solid substrate carrying a magnetically anisotropic film consisting of a transition metal-rare earth alloy, wherein the transition metal component is selected from the group consisting of cobalt, iron, nickel, manganese and alloys thereof, and wherein the rare earth metal component is selected from the group consisting of the 15 elements of the lanthanide series having atomic numbers 57 to 71 and the element yttrium and mixtures thereof, said alloy film being continuous coherent and substantially uniform, said alloy film having a thickness ranging from about 100 Angstroms to about 10,000 Angstroms and having an easy axis of magnetization significantly aligned perpendicular to the plane of the sub-strate, and said substrate being substantially inert only at temperatures ranging up to 1000° C.

8. A magnetic member according to claim 7 wherein said alloy film ranges in thickness from about 300 Angstroms to 1000 Angstroms.

9. A magnetic member according to claim 7 wherein the substrate is a flexible copper tape.

10. A magnetic member according to claim 7 wherein said alloy is Co5Sm.

11. A magnetic member according to claim 7 wherein said alloy film has a coating of an inert non-magnetic material which prevents oxidation and deterioration of the magnetic properties of the alloy film.

12. A magnetic member according to claim 11 wherein said coating of inert non-magnetic material is shellac.